Sébastien Chabal, the Sale No8 who scored the winning try for France against England at Twickenham last weekend, will miss Saturday's return match in Marseille because of a calf problem.

While Chabal's absence is precautionary, the prop Sylvain Marconnet, who has not played for six months after injuring his leg in a skiing accident, has yet to have a date set for a return to action. He will be assessed by France's medical team tomorrow, though the team manager, Jo Maso, yesterday said time was running out. France's other tight-head specialist, Pieter de Villiers, who pulled out of the side which defeated England because of a calf injury, will also be in the stands on Saturday. Like Chabal he is expected to be fit for the match against Wales at the Millennium Stadium on August 26.

France's coach, Bernard Laporte, who announced his World Cup squad in June, will tinker with his starting line-up against England as he ponders his side for the tournament opener against Argentina on September 7. Jean-Baptiste Elissalde will replace Pierre Mignoni at scrum-half, the Sale hooker Sébastien Bruno replaces Dimitri Szarzewski in the 22 and the wing Christophe Dominici has been recalled.

"We want to give more players a chance," said Maso. "England have said they will field their strongest side [an intention forcibly amended yesterday], and that is a frightening prospect when they have catalysts like Jonny Wilkinson, but we won at Twickenham without doing well in the set pieces and that is an area we are looking for a big improvement in."

South Africa, England's main rivals in the group stage, confirmed the withdrawal of the No8 Pierre Spies from their World Cup squad. The Springboks had asked for a third medical opinion on the blood clots on the forward's lungs, in the hope that he would be able to play some part in France but Spies has been put on blood-thinning medication for the next three months and told not to play any contact sports.

The United States, another of England's Pool A opponents, announced their World Cup squad yesterday. It includes the Leeds prop Mike MacDonald, the Doncaster second-row Luke Gross and the Newport-Gwent Dragons centre Paul Emerick, but most of the players are home-based amateurs. "We will be facing two really tough international sides in the World Cup and could have done with better preparation," said the USA coach, Peter Thorburn, the former Bristol director of rugby whose side will warm up against Munster in Chicago on August 26.

Romania's squad includes the centre Romeo Gontineac, who will become the country's first player to appear at four World Cups, and the Perpignan flanker Ovidiu Tonita.